1. Field of the Invention
The present invention relates to a tool interchanging apparatus for a press machine and, more particularly, to a press tool interchanging apparatus using a tool plate arranged with pressure fluid conduits.
2. Description of the Prior Art
In the prior art of press working field required to have a multiple-kind little production, it has grown ordinary to interchange press tools ten and more times a day. In order to keep and improve the working efficiency of the press machine, therefore, it is one of important factors to shorten the tool interchanging time. Thus, a variety of tool interchanging apparatus have been devised. In this meanwhile, however, the press facilities are large-sized, and a mere improvement in the existing facilities could not cope with the demand of the field. Many other problems are left unsolved in that the shortening of the tool interchanging time and the spare of the man power are insufficient and ineffective. It is well known in the art, for example, to interchange the tools by moving in and out a tool plate carrying a press tool at a right angle with respect to the work conveying direction or by moving it further in parallel with the work conveying direction (as disclosed in Japanese Patent Laid-Open Nos. 57519, 248762 and 126233/1991). Some of these disclosures uses a self-running truck which is made to run on a pair of rails. However, this tool interchanging apparatus using the self-running truck is required to reinforce the floor, on which are laid the rails, thus inviting an increase in the construction cost.
In case a tool plate carrying a press tool is to be lifted from the bolster plate of a press machine by means of built-in lifters and horizontally conveyed on a roller conveyor, it is also known in the art to use a pusher or a closed loop chain with pawls. On the other hand, an automatic clamp for clamping the press tool and a tool plate or a bolster plate usually uses a hydraulic cylinder. However, pressure fluid conduits for feeding a fluid such as oil under pressure to those lifters or auto clamps are separately arranged by metal tubes or naked high-pressure hoses.
The auto clamps or lifters have to be fed with the pressure fluid so as to position the press tool, which has been moved horizontally or vertically and seated on the stationary bolster plate of a press station, to fixe at least the lower tool member on the bolster plate and to move the press tool again.
In the press tool interchanging apparatus of the prior art, however, the operator has to enter the dangerous inside of the press machine, after he has stopped the press machine, to connect the flexible tubes of the fluid conduits of the auto clamps and the tool lifters manually for each interchange. This operation is not only troublesome but also liable to invite leakage of the pressure fluid. Another problem is to take a long time for the connection.